Exposure control system



April 23, 1968 J. E. BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet i Filed Oct.

INVENTORS BY W M Mm A T TORNE VS April 23, 1968 J. E. BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 2 Filed Oct.

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EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 5 Filed Oct.

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EXPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 19 Sheets-Sheet .1

INVENTORS. JOHN E'.- BLACKERT BY DOUGLAS E.WEBB

ATTORNEYS April 23, 1968 J. E. BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 19 Sheets-Sheet 5 FIG. 5

INVENTORS JOHN E. BLACKERT DOUGLAS E. WEBB A T TORNE VS April 23, 1968 BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 19 Sheets-Sheet Wig & w it 5% S2 mvEmoRs L JOHN E. BLACKERT DOUGLAS E. WEBB A T TORNE Y5 April 23, 1968 J BLACKER-r ET AL 3,379,110

EXPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 19 Sheets-Sheet 'x FIG. 8

INVENTORS JOHN E. BLACKERT DOUGLAS E. WEBB BY @WM A T TORNEVS J. BLACKERT ET AL 3,379,110

April 23, 1968 EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 5 Filed Oct.

INVENTORS BLACKERT JOHN BY DOUGLAS E. WEBB A TTORNEYS April 23, 1968 Filed Oct l, 1965 J. E. BLACKERT ET EXPOSURE CONTROL SYSTEM 1,9 Sheets-Sheet a1 INVENTORS E. BLACKERT ATTORNEYS J. E. BLACKERT ET AL 3,379,110

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April 23, 1968 BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 112 Filed Oct.

S V M B M 6 O B N Mm R c m A T N E s a W 5 Y B A ril 23, 1968 .1. E. BLACKERT ET AL 3,379,110

EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 1.5

.iled Oct.

INVENTORS BLACKERT E. WEBB dds Lj A TTORNEYS mum JOHN BY DOUGLAS April 23, 1968 J BLACKERT ET AL 3,379,110

E/XPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 19 Sheets-Sheet 14 INVENTORS. JOHN E. BLACKERT DOUGLAS E.WEBB

A TTORNE Y8 A ril 23, 1968 .1. E. BLACKERT T AL 3,379,110

EXPOSURE CONTROL SYSTEM Filed Oct. 1, 1965 l9 Sheets-Sheet l5 INVENTORS JOHN E. BLACKERT DOUGLAS E. {EBB BY a -PM ATIORNEYS J. E. BLACKERT ET AL 3,379,110

April 23, 1968 EXPOSURE CONTROL 5 Y8 TEM l9 Sheets-Sheet 16 T m M 5 M E m M c 0 W A EA P L NG w mo Y B April 23, 1968- J. E. BLACKE RT ET AL 3,3 9,1

EXPOSURE CONTROL SYSTEM 19 Sheets-Sheet 17 Filed Oct.

\/\r MODULATOR SEPARATION AMPLIFIER H'EATER] SUPPLY HEATER SUPPLY INVENTO H6. 2/ JOHN E. BLACKER'? DOUGLAS E. WEBB A TTORNEYS A ril 23, 1968 Filed Oct. 1, 1965 J. E. BLACKERT ET AL EXPOSURE CONTROL SYSTEM POWER SUPPLY TH T'W T 1- POWER SUPPLY l9 Sheets-Sheet 15 INVENTORS. JOHN E. BLACKERT DOUGLAS E.WEBB

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ATTORNEYS April 23, 1968 J. E. BLACKERT ET 3,379,110

EXPOSURE CONTROL SYSTEM I Filed Oct. 1, 1965 i 19 SheetsSheet 19 Try INVENTORS E. BLACKERT ATTORNEYS JOHN BY DOUGLAS E. WEBB a United States Patent Office 3,379,110 Patented Apr. 23, 1968 3,379,110 EXPGSURE CONTROL SYSTEM John E. Blaclrert and Douglas E. Webb, Webster, N.Y., assignors to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed Oct. 1, 1965, Ser. No. 491,919 10 Claims. (CI. 95-75) This invention relates to photography and, more particularly, to producing contact exposure of raw photographic materials from photographic negatives.

In contact printing, as the name implies and as understood in the art, sensitized duplicating film, paper, or the like, is exposed while in physical contact with a negative to be reproduced. As used herein, the term negative is intended to encompass a transparency on which the image can be either a negative or positive in a photographic sense. Generally speaking, care must be exercised for selecting the proper exposure for the differing densities on the negative so that a proper tonal reproduction may be had on the positive print. A common method to control exposure in contact printing is by the use of one or more lights in conjunction with an optical system made up of adjustable filters and mirrors to compensate for the variable density areas on the negative, as indicated, for example, in US. Patent 3,141,398. By this technique, with each dilferent negative exposed, time consuming adjustments must be made to the optics to compensate for uniform illumination of the light and dark areas on the negative. This type of exposure system is also limited by the frame size which it can uniformly illuminate.

With the present-day demand for mass production of photographic exposures of the highest possible quality, resolution, and acutance from roll film negatives, such as those used in aerial photography, the existing systems are generally unsuitable. The exposure control of the contact printer must be capable of not only responding to varying density levels on the negative film and compensating for them but must also accommodate frame sizes which vary, for example, from 70 millimeters to about 10 inches in width and up to about 30 inches in length. To meet these requirements, a contact printer requires an automatic exposure control having maximum information transfer with built-in flexibility to compensate for characteristics in both the negative and duplicating film While maintaining a resolution in the film print as high as 800 lines/mm.

It is, therefore, an object of this invention to provide methods and apparatus for producing photographic exposures of high quality, resolution, and acutance from roll film negatives.

It is another object of this invention to provide methods and apparatus for achieving automatic exposure control of negatives varying in frame size in a simplified manner.

It is still another object of this invention to provide an automatic exposure control system in a contact printer capable of high print rates.

It it still a further object of this invention to provide automatic exposure control methods and apparatus that compensae for underexposure or overexposure of the negative to be reproduced.

It is still a further object of this invention to provide automatic exposure control methods and apparatus that produce maximum detail according to the contrast characteristics of the duplicating material.

These and other features and objects of the invention will be apparent from the following description and from the drawings in which:

FIGURE 1 is a perspective view of the exterior of the contact printer apparatus hereof;

FIGURE 2 is an enlarged view of the control panel;

FIGURE 3 is an isometric view of the contact printer apparatus;

FIGURE 4 is a side elevation of the contact printer with the doors removed;

FIGURE 5 is an end view of the contact printer apparatus;

FIGURE 6 is a plan view of the window shade assembly;

FIGURE 7 is an enlarged view of the storage loop assembly with portions broken away to show internal structure;

FIGURE 8 is a front view of FIGURE 7;

FIGURE 9 is a view of the variable coefficient damper assembly with portions broken away to show internal structure;

FIGURE 10 is a view of the transport capstan assembly;

FIGURE 11 is a block diagram of the system for starting and stopping the film transport;

FIGURE 12 is a longitudinal sectional view of the film drive support;

FIGURES 13A through 13F are sectional views of the film drive support taken along lines AA through F-F, respectively, of FIGURE 12;

FIGURES 14 and 15 are a plan and side view, respectively, of the articulated idler assembly;

FIGURES 16 and 17 are side elevation and plan views, respectively, of the film gate assembly partly broken away to show internal components;

FIGURE 18 is an end view of the gate assembly taken along line 18--18 of FIGURE 16;

FIGURE 19 is a sectional view of the lamp house assembly taken along line 19-49 of FIGURE 16;

FIGURE 20 is another sectional view of the lamp house assembly taken along line 20-20 of FIGURE 17;

FIGURE 21 is a block diagram illustrating the exposure control system;

FIGURE 22 is a schematic electrical diagram of the separation amplifier for the exposure control system; and

FIGURE 22 is an electrical circuit diagram of the scan drive and gate assembly.

Referring now to FIGURE 1 of the drawings, the apparatus includes a cabinet 11 having a control panel 12 on which are mounted various selector knobs, buttons, and indicators used for controlling the operation of the machine. For example, certain controls are used to set the printing cycle, while others determine inputs to the automatic exposure control system in a manner which will become apparent. Observation by an operator of the frame position of the negative is obtained through 'a glass viewer 14 adjacent the control panel. The interior of the printer is protected from light entering through viewer 14 by a suitable light shield not shown. On the sides of the cabinet are sliding doors 15 through which entry may be made for loading the negative and duplicating material and for general servicing of the apparatus.

As best shown in FIGURE 2, control panel 12 has an ON button 17, an OFF button .18, and a standby button 19 which when depressed brings the machine to a controlled stop. Directly below these buttons are a printsin-run counter 21 and a prints-per-frame selector 23 which indicate the total number of prints and prints for each frame, respectively. For manually positioning the negative film there is a lever 24 connected to a potentiometer that controls the drive of the film which can be observed through viewer 14. Also located on the panel are negative wind button 25 and rewind button 26 for rapidly positioning the negative film. A display counter 27 that is set at a reference datum indicates the portion of the negative at the viewer in either feet or frames from the preset reference. Metering of counter 27 in footage or frame numbers is determined by depressing buttons 28 and 29, respectively. A search/repeat counter 

9. PHOTOGRAPHIC EXPOSURE APPARATUS COMPRISING IN COMBINATION: (A) A TRANSPARENT PLATEN FOR SUPPORTING AN IMAGE TRANSPARENCY TO BE REPRODUCED; (B) MEANS FOR SUPPORTING A LIGHT SENSITIVE DUPLICATING MATERIAL IN OVERLYING CONTACT WITH SAID IMAGE TRANSPARENCY; (C) LAMP HOUSE MEANS DEFINING AN APERTURE SLIT POSITIONED TO ILLUMINATE AN INCREMENTAL AREA ON SAID IMAGE TRANSPARENCY, SAID LAMP HOUSE MEANS COMPRISING: (1) AN ULTRAVIOLET EXPOSING LIGHT, (2) A RED SENSING LIGHT, AND (3) A DICHORIC MIRROR OPTICALLY POSITIONED TO REFLECT SAID ULTRAVIOLET LIGHT AND CONDUCT SAID RED LIGHT THROUGH SAID SLIT; (D) A RED COLORED MEMBER POSITIONED IN SURFACE CONTACT WITH SAID DUPLICATING MATERIAL, SAID RED COLORED MEMBER BEING OPERATIVELY CONNECTED TO SAID LAMP HOUSE MEANS FOR MOVEMENT THEREWITH; (E) AN ARRAY OF LIGHT SENSORS OPTICALLY POSITIONED WITHIN SAID RED COLORED MEMBER TO RECEIVE THE RED SENSING LIGHT ILLUMINATED FROM THE SLIT IN SAID LAMP HOUSE HOUSE MEANS; AND (F) CIRCUIT MEANS RESPONSIVE TO THE INTENSITY OF SAID RED SENSING LIGHT AS DETERMINED BY SAID SENSORS FOR MODULATING THE INTENSITY OF SAID ULTRAVIOLET EXPOSING LIGHT. 